Manually operated encapsulated single pole-double throw high voltage vacuum switch



Feb. 4, 1969 w. HANSEN 3,426,168

MANUALLY OPERATED ENCAPSULATED SINGLE POLE-DOUBLE THROW HIGH VOLTAGE vacuum SWITCH Filed July 16, 1965 A'IIIQ'II'II/lll'. i' '9 l7 l6 I, r

INVENTOR.

ROBERT W- HANSEN United States Patent 1 Claim ABSTRACT OF THE DISCLOSURE A,high voltage vacuum switch in which a vacuum switch assembly is encapsulated within an outer housing. The switch assembly includes a hermetically tight envelope enclosing fixed and movable switch contacts. Plunger means journaled in the outer housing is connected to an actuator rod which embodies the movable switch contact. Preferably the switch envelope is supported in the housing by a dielectric cushioning material.

One of the objects of the invention is to provide a low cost vacuum micro-switch, and more particularly, to provide a manually operated high voltage vacuum microswitch.

Switches of various conventional design are available which function in response variations in temperature or pressure, which operate upon minute displacement of a lever arm by an outside force, or which are controlled in a variety of other ways. So far as is known, none of these conventional switches have been fabricated so as to utilize a vacuum envelope. Occasionally, switches are hermetically sealed but so far as is known no effort has been made to evacuate the envelope or case of -a switch, probably because of prohibitive costs. In the present invention it is one of the principal objects of the invention to provide at relatively low cost a switch in which the contact points are enclosed within a vacuum envelope.

In conventional switches which are essentially lowvoltage devices the contacts make and break in an air atmosphere having low electrical resistance, especially after an arc has occurred which causes ionization of contact material in the vicinity of the contacts. Such arcing also causes pitting of the contacts .and eventual destruction. Accordingly it is another object of the invention to provide a switch in which the contacts are enclosed in a vacuum and which is suitable for high voltage applications.

It is another object of the invention to provide an encapsulating dielectric envelope for the switch in order to adequately protect fragile portions of the switch against rupture and to form a convenient mounting base for the vacuum switch.

Conventional switches which utilize a resilient blade having a contact point mounted on .the end thereof are unreliable in some environments, such as rockets and space craft, because the acceleration and deceleration forces encountered in such flights have the effect of actuating the switch at other than the predetermined instant which it is scheduled to operate. Accordingly, it is a still further object of the present invention to provide a switch which is not susceptible to inadvertent operation due to acceleration and deceleration forces.

Conventional vacuum switches require extensive and costly processing to achieve the requisite degree of vacuity. The application of vacuum switches has been limited by this costly processing. Therefore, another object of this invention is to provide a relatively inexpensive vacuum switch in conjunction with an actuating mechanism which permits manual operation of the switch.

3,426,168 Patented Feb. 4, 1969 The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawing. It is to be understood however that the invention is not limited to the embodiment illustrated and described, but may be embodied in various forms within the scope of the appended claims.

Referring to the drawings:

FIG. 1 is a vertical cross-sectional view taken in the plane indicated by the line 11 in FIG. 3.

FIG. 2 is an end view taken in the direction indicated by the arrow 2 in FIG. 1.

FIG. 3 is a plan view taken in the direction indicated by the arrow 3 in FIG. 1.

Broadly considered, the manually operated single poledouble throw high voltage encapsulated vacuum switch of the invention comprises an outer encapsulating housing possessing a hollow interior Within which is embedded a vacuum switch similar to the one disclosed in my copending application Ser. No. 448,322. As there indicated, the switch comprises a generally tubular dielectric envelope closed at each opposite end by an end cap assembly which functions also as a terminal electrode. One of the end cap assemblies also funtcions as a fixed contact adapted to make contact with a movable contact rod laterally displaceable within the evacuated envelope of the switch. Intermediate the two end cap assemblies is a second fixed electrode adapted to make contact with an intermediate portion of the movable contact rod upon lateral displacement thereof. Connecting leads extend from the terminal electrodes out of the encapsulating housing. Means are provided slidably journaled on the encapsulating housing and engaging the actuating rod of the switch to effect lateral displacement thereof to make or break a circuit through the micro-switch.

In terms of greater detail, the high voltage vacuum switch of the invention comprises an outer dielectric encapsulating housing 2, having therewithin a hollow chamber 3, within which is enclosed a vacuum switch 4 similar to that disclosed in my copending application Ser. No. 448,322. As there described, the vacuum switch comprises a pair of axially aligned tubular dielectric members 6 and 7, closed at each opposite end by metallic end cap assemblies 8 and 9, with a tubulation 12 hermetically brazed in the end cap 8. The end cap 9 functions as a flexible diaphragm on which is supported an actuating rod 13, a center section of which functions as an intermediate contact 14, with an end portion of the actuator rod functioning as a second mobile contact 16 within the envelope.

In the present embodiment of the switch enclosed within the encapsulating housing 2, the parts are proportioned to permit the vacuum switch to lie spaced between the side walls of the encapsulating member 2 and to be resiliently supported therebetween by a body of resilient dielectric cushioning material 17. This material may conveniently be a silicon rubber or a resilient synthetic resin which is appropriately formed around the vacuum switch so as to fill the cavity therearound without voids.

At the end of the vacuum switch adjacent the flexible diaphragm 9, the cushioning material is eliminated, and a portion 18 of the actuator stem 13 extends transversely into the chamber 3 formed in the encapsulating housing 2. The end of the portion 18 of the actuator shaft is appropriately caught in the end of a plunger 19, preferably fabricated from a dielectric material, and slidably journaled in a bore 21 formed in one wall of the encapsulating housing 2. A head portion 22 is provided on the plunger 19 outside the housing. At its other end, the plunger is resiliently supported by a coil spring 23. The proportions of the parts is such that the coil spring exerts a resilient force upwardly on the portion 18 of the actuator stem as viewed in FIG. 1, thus causing the actuator rod at its left end as viewed in FIG. 1 to be displaced downwardly into the position shown so as to bring the end 16 of the actuator rod into electrical contact with the interior surface of the tubulation 12. It will thus be seen that in this position of the parts a circuit is normally made through the outermost pair of terminal leads.

Upon manual depression of the plunger by place of a finger on the head 22, the spring 23 is compressed and the actuator rod 13 is caused to pivot clockwise as viewed in FIG. 1. This will bring the intermediate contact portion 14 of the actuator rod into electrical contact with the intermediate electrode 24 and complete a circuit between the intermediate terminal and the terminal lead connected to the diaphragm 9. When finger or other pressure is removed from the plunger, the spring 23 will etfect movement of the actuator rod counter-clockwise to effect disengagement of the intermediate movable contact 14 from the fixed contact 24 and cause reengagement of the movable contact 16 with the tubulation 12.

In order to mount the switch on a supporting structure, a pair of eyelets 26 are provided at opposite ends of the encapsulating housing. It will thus be seen that the microswitch may be mounted in any desired position and adjusted so that the requisite amount of displacement is provided to the plunger 19' to effect operation of the switch.

I claim:

1. A high voltage vacuum switch comprising a hollow outer housing having a walled cavity therein, a vacuum switch assembly including a hermetically tight envelope enclosing a fixed switch contact therein and an elongated actuator rod movably supported on the envelope with one end of said rod extending outside of said envelope and the other end of said rod providing a movable switch contact within said envelope, said vacuum switch assembly being fixed within said cavity of the outer housing in a manner permitting said one end of said rod to be movable laterally in said cavity, plunger means journaled in the wall of the outer housing for sliding movement along an axis transversing the longitudinal axis of said elongated rod, said plunger means including at one end a dielectric portion connected to said one end of said rod and having its other end accessible to manipulation from outside the outer housing to make or break a circuit through the switch, terminal means connected to said fixed and movable contacts respectively and extending outside of the outer housing for connection into a circuit, said switch assembly envelope being spaced from the inner walls of the cavity to provide a space therebetween and said space, except for the area surrounding said one end of said rod and said plunger means, being filled with a body of resilient dielectric cushioning material which supports said envelope in said cavity, said plunger means being formed of dielectric material, said plunger means being directly journaled in the wall of said outer housing and is directly connected to said one end of said rod.

References Cited UNITED STATES PATENTS 2,527,475 10/ 1950 Bates 200-144 2,842,644 7/1958 Korsgren 200-168 3,037,099 5/ 1962 Aandewiel 200-168 3,123,698 3/1964 Waterton 200-144 3,147,356 9/1964 Luehring 200-144 2,573,514 10/1951 Turner 200-159 ROBERT S. MACON, Primary Examiner.

US. Cl. X.R. 200-159, 168 

